DTAG-3

The DTAG-3 was designed in 2010-12 at the Woods Hole Oceanographic Institution by Johnson, Hurst and Shorter as a complete revision of the DTAG-2. Objectives were to (i) halve the volume of the tag so as to make it suitable for small odontocetes, and (ii) increase the recording time and/or bandwidth of the tag. Interfaces for new sensors were also included along with a more powerful processor, increased memory capacity and a full speed USB interface. To meet the size goal, an integrated design approach was adopted leading to a compact fully-cast design. The electronic cavity in the forward section of the tag is either oil-filled or cast in epoxy. The rear section houses the syntactic foam floatation and the entire tag is over-potted in polyurethane. The tag still has four suction cups but these are now x mm diameter each and mount directly on the tag body. The 220 MHz VHF beacon is now powered from the same rechargable battery as the tag electronics to save weight and a watch-dog microprocessor manages the battery to ensure that sufficient charge is kept for tag recovery.
The DTAG-3 has 32-64 GB of memory and has a recording time of up to 3 days depending on sampling rate. Several versions of the DTAG-3 have been built with different sensor suites. These include high-frequency stereo tags with 160 kHz recording bandwidth for porpoises, as well as tags with gyroscopes, GPS and ECG sensors. A DTAG-3 with a 1.5 MHz echosounder is currently being tested. A new long-duration version of the DTAG-3 for use on seals is also being designed. This will include an Argos transmitter and a Lithium primary cell giving up to 1 month of continuous recording time. An early version of this device is currently being used as a passive acoustic monitor on ocean gliders.

DTAG3 assembled and ready for encapsulation. The electronics are inside the grey box which is filled with urethane gel. The balls on the left are the two hydrophones. The syntactic foam flotation is on the right of the image. Photo: Tom Hurst / WHOI.

These include functions for extracting information from the XML records and for accessing data from the sensor and audio files generated by D3 devices. To use these tools you should also download the general tag tools: